Abstract
We investigated the relations of the amounts of various soil organic substances by the WAKSMAN's analysis to soil biomass and soil respiration rate in order to establish a procedure for assessing easily decomposable organic substance in soil. The soil samples used were collected from 4 upland fields that received organic amendment continuously. The amounts of hot water-soluble organic substance, 2% HCl hydrolyzable saccharide, and 80% H_2SO_4 hydrolyzable saccharide in soil were determined by the WAKSMAN's proximate analysis. High positive correlation was found between the amount of hot water-soluble organic substance and the soil biomass. The rate of soil respiration was also highly correlated with the amount of hot water-soluble organic substance. From these results, we suggest that the assessment of easily decomposable organic substance in soil is possible through the measurement of hot water-soluble organic substance. The weakness of the interaction between hot water-soluble organic substance and other soil components seems to support our suggestion.
